U.S. patent application number 11/306925 was filed with the patent office on 2008-06-12 for coordination of electronic counter measures.
This patent application is currently assigned to SAAB AB. Invention is credited to Niklas Ferm, Thomas Lindvall.
Application Number | 20080136701 11/306925 |
Document ID | / |
Family ID | 34933376 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080136701 |
Kind Code |
A1 |
Ferm; Niklas ; et
al. |
June 12, 2008 |
Coordination of Electronic Counter Measures
Abstract
An electronic counter measures solution. Jamming signals are
emitted towards a threat to improve chances of survival for at
least two vehicles, which are physically separated from one
another, however associated with one another in a group. Each of
the at least two vehicles receives a wireless time reference signal
from an external resource. The vehicles exchange messages over a
wireless data link. The messages pertain to usage of at least one
electronic warfare resource in each vehicle. Based on the messages
and the time reference signal the usage of at least one first
electronic warfare resource in a first vehicle is coordinated with
the usage of at least one second electronic warfare resource in a
second vehicle, such that a particular type of jamming signal is
emitted alternately either from the at least one first resource or
from the at least one second resource, essentially without any
overlaps or gaps in time. Thereby, a false target is created
between the vehicles with respect to a weapon which operates in a
so-called Home-on-Jam mode.
Inventors: |
Ferm; Niklas; (Linkoping,
SE) ; Lindvall; Thomas; (Linkoping, SE) |
Correspondence
Address: |
VENABLE LLP
P.O. BOX 34385
WASHINGTON
DC
20043-9998
US
|
Assignee: |
SAAB AB
Linkoping
SE
|
Family ID: |
34933376 |
Appl. No.: |
11/306925 |
Filed: |
January 17, 2006 |
Current U.S.
Class: |
342/14 ;
342/57 |
Current CPC
Class: |
H04K 3/65 20130101; H04K
2203/24 20130101; H04K 2203/36 20130101; H04K 2203/34 20130101;
H04K 3/825 20130101; H04K 2203/22 20130101; G01S 7/38 20130101 |
Class at
Publication: |
342/14 ;
342/57 |
International
Class: |
G01S 7/38 20060101
G01S007/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2005 |
EP |
05001071.9 |
Claims
1. A method of producing jamming signals comprising: receiving a
wireless time reference signal from an external resource,
exchanging messages over a wireless data link, and generating at
least one type of jamming signal based on the time reference signal
and the messages, the at least one type of jamming signal being
emitted from two or more stations physically separated from one
another and associated with one another in a group of stations,
wherein the messages comprise data pertaining to a usage of at
least one first electronic warfare resource in a first station in
the group and at least one second electronic warfare resource in at
least one second station in the group, and coordinating the usage
of the at least one first and second resources based on the
messages and the time reference signal, such that a particular type
of jamming signal is emitted alternately either from the at least
one first resource or from the at least one second resource
essentially without any overlaps or gaps in time.
2. The method according to claim 1, further comprising: specifying
signal parameter information pertaining to a number of known
threats; specifying a counter measure library containing a complete
set of electronic warfare resources comprising any resources which
are included in at least one station of the group; and identifying,
for each of said threats, at least one of the resources in the
complete set of electronic warfare resources which is estimated to
constitute an appropriate counter measure to combat the threat.
3. The method according to claim 2, further comprising: specifying
a time synchronizing pattern describing a timing profile for a
jamming signal to be emitted from each resource in the complete set
of electronic warfare resources in respect of each of said known
threats.
4. The method according to claim 1, further comprising: specifying,
in each station, for each electronic warfare resource included in
this station whether the resource is currently available or not for
emitting jamming signals; exchanging, repeatedly, status messages
with the other stations in the group, each message reflecting a
current availability of the electronic warfare resource included in
the station from which the message is transmitted; and recording,
based on any received status messages from the other stations in
the group, a resource activation status for each resource of the
electronic warfare resource included in the other stations in the
group.
5. The method according to claim 4, wherein each station in the
group is associated with at least one threat warning system, and
the method further comprising: determining, based on an output from
the at least one threat warning system and the resources activation
statuses, in a first station in the group whether at least one
particular threat is appropriate to combat by means of a first
electronic warfare resource in this station in coordination with at
least one second electronic warfare resource in at least one second
station in the group; and if such a coordination is found to be
appropriate transmitting a request message from the first station
to the at least one second station; waiting for at least one reply
message to be returned from the at least one second station in
response to the request message; and if at least one of any
received reply messages indicates a service accept emitting a
jamming signal from the first electronic warfare resource in
coordination with a jamming signal emitted from each of the at
least one second electronic warfare resource in the at least one
second station having replied with a message indicating a service
accept.
6. The method according to claim 5, further comprising: maintaining
the emission of the jamming signals (J.sub.A; J.sub.B) until the at
least one threat warning system indicates that all threats being
combated by the jamming signals have ceased to constitute threats,
or a deactivation order is received from the at least one second
station in respect of the jamming signals.
7. The method according to claim 1, wherein the coordination of the
usage of the at least one first and second resources comprises:
determining an absolute point in time when the emission of the
particular type of jamming signal shall begin; and determining a
time synchronizing pattern for the emission the particular type of
jamming signal from the first electronic warfare resource and the
at least one second electronic warfare resource.
8. A computer program product, comprising: a computer readable
medium; and computer program instructions recorded on the computer
readable medium and executable by a processor for producing jamming
signals, wherein the computer program instructions for carrying out
a method comprising: receiving a wireless time reference signal
from an external resource, exchanging messages over a wireless data
link, and generating at least one type of jamming signal based on
the time reference signal and the messages, the at least one type
of jamming signal being emitted from two or more stations
physically separated from one another and associated with one
another in a group of stations, wherein the messages comprising
data pertaining to a usage of at least one first electronic warfare
resource in a first station in the group and at least one second
electronic warfare resource in at least one second station in the
group, and wherein the program code comprising instructions for
coordinating the usage of the at least one first and second
resources based on the messages and the time reference signal, such
that a particular type of jamming signal is emitted alternately
either from the at least one first resource or from the at least
one second resource essentially without any over-laps or gaps in
time.
9. A computer program product in a computer readable medium having
computer program code recorded thereon, wherein the program code
includes sets of instructions comprising: first computer
instructions for exchanging messages (D) over a wireless data link
(L), and second computer instructions for generating at least one
type of jamming signal (J.sub.A; J.sub.B) based on the time
reference signal (T) and the messages (D), the at least one type of
jamming signal (J.sub.A; J.sub.B) being emitted from two or more
stations (100, 200, 300) physically separated from one another and
associated with one another in a group of stations, wherein the
messages (D) comprising data pertaining to a usage of at least one
first electronic warfare resource (R.sub.11i) in a first station
(100) in the group and at least one second electronic warfare
resource (R.sub.21) in at least one second station (200) in the
group, and third computer instructions for coordinating the usage
of the at least one first and second resources (R.sub.11, R.sub.21)
based on the messages (D) and the time reference signal (T), such
that a particular type of jamming signal (J.sub.A; J.sub.B) is
emitted alternately either from the at least one first resource
(R.sub.11) or from the at least one second resource (R.sub.21)
essentially without any overlaps or gaps in time.
10. An electronic counter measures station for radiating jamming
signals, comprising: a receiver unit adapted to receive a wireless
time reference signal from an external resource; a communication
unit adapted to exchange messages over a wireless data link; and at
least one electronic warfare resource adapted to generate and emit
at least one type of jamming signal based on the time reference
signal and the messages, wherein the communication unit is adapted
to exchange the messages with at least one other electronic counter
measures station which is physically separated from the station and
is associated with the station to form a group of stations; the
messages comprise data pertaining to a usage of the at least one
first electronic warfare resource and at least one corresponding
second electronic warfare resource in at least one other electronic
counter measures station in the group; and the station comprises a
resource handling unit adapted to, based on the messages and the
time reference signal, coordinate the usage of the at least one
first and second resources such that a particular type of jamming
signal is emitted alternately either from the at least one first
resource or from the at least one second resource essentially
without any overlaps or gaps in time.
11. The station according to claim 10, further comprising: a
database including: a threat library specifying signal parameter
information pertaining to a number of known threats; a counter
measure library specifying a complete set of electronic warfare
resources containing any resources which are included in at least
one of the stations in the group; and a table which for each of
said threats identifies at least one of the resources in the
complete set of electronic warfare resources that is estimated to
constitute an appropriate counter measure to combat the threat.
12. The station according to claim 11, wherein the counter measure
library for each resource in the complete set of electronic warfare
resources specifies a time synchronizing pattern describing a
timing profile for a jamming signal to be emitted by the resource
in respect of each of said known threats.
13. The station according to claim 10 wherein the resource handling
unit is adapted to repeatedly control the communication unit to
exchange status messages with the other stations in the group, each
message reflecting a current availability of the electronic warfare
resource included in the station from which the message is
transmitted.
14. The station according to claim 13, wherein the resource
handling unit comprises: a local resource listing which for each
electronic warfare resource included in the station specifies
whether the resource is currently available or not for emitting
jamming signals; and a group resource listing which specifies an
activation status for each electronic warfare resource included in
the at least one other station of the group; and wherein the
resource handling unit is adapted to update the group resource
listing with a current resource activation status for each resource
of the electronic warfare resource included in the other stations
in the group based on any received status messages from the other
stations in the group.
15. The station according to claim 14, wherein the station is
associated with at least one threat warning system, and the
resource handling unit is adapted to: determine, based on an output
from the least one threat warning system and the resources
activation statuses, whether at least one particular threat is
appropriate to combat by means of a first electronic warfare
resource in this station in coordination with at least one second
electronic warfare resource in at least one second station in the
group; and if such a coordination is found to be appropriate
control the communication unit to transmit a request message from
the first station to the at least one second station; control the
communication unit to wait for at least one reply message being
returned from the at least one second station in response to the
request message; and if the least one reply message indicates a
service accept emitting a jamming signal from the first electronic
warfare resource in coordination with a jamming signal emitted from
each of the at least one second electronic warfare resource in the
at least one second station having replied with a message
indicating a service accept.
16. The station according to claim 15, wherein the resource
handling unit is adapted to maintain the emission of the jamming
signals until the at least one threat warning system indicates that
all threats being combated by the jamming signals have ceased to
constitute threats, or the communication unit receives a
deactivation order from the at least one other station in respect
of the jamming signals.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to electronic
warfare and electronic counter measures. More particularly the
invention relates to a method of producing jamming signals and
electronic counter measures stations.
BACKGROUND OF THE INVENTION
[0002] Electronic warfare systems play an increasingly important
role in modern battle scenarios. Tactical electronic warfare assets
are therefore included in almost every new military land, sea or
air vehicle. These assets may primarily be used for the purposes of
self-protection (i.e. jamming an enemy weapon and/or vehicle to
decrease the quality of any measurements performed by this weapon
and/or vehicle, and thereby improve the chances of own survival),
or for the purposes of generating a background noise intended to
improve the protection of the vehicle itself, or other vehicles
included in a fleet or group of vehicles. The input data for
controlling the vehicle mounted electronic warfare resources is
here either derived from an interception receiver on each vehicle,
preplanned actions or manually initiated operations performed by an
operator/driver. Any coordinated radiation of jamming signals from
different vehicles is primarily accomplished via verbal
communication between the operators/drivers of the vehicles and
manual actions executed by these persons.
[0003] However, the document U.S. Pat. No. 6,697,008 describes a
distributed electronic warfare system wherein a central control
site automatically coordinates jamming signals radiated from a
plurality of electronic warfare pods attached to a variety of
aircrafts, such that an improved jamming effect is attained against
a particular target. Moreover, by means of GPS-based time
synchronization and a central processing of signals received from a
particular target in a plurality of pods, geolocation of the
particular target is enabled.
[0004] The document BE, 1 011 770 A4 discloses a method for angular
radio-electric scrambling of a radar tracking device. Two aircrafts
here cooperate, so that a radar signal from a hostile vehicle
received by a first aircraft (located in the range of the main lobe
of the vehicle's aerial transmitter) is transmitted to a second
aircraft (located outside the range of the main lobe). In addition
to a signal reflection from the first aircraft, the second aircraft
radiates a similar signal towards the hostile vehicle, which is
based on the signal transmitted from the first aircraft. Thereby,
the enemy vehicle registers an angular error in respect of the
radar echo from the first aircraft, such that the first aircraft's
risk of being struck by the hostile vehicle's weapons is reduced.
Nevertheless, neither the first nor the second aircraft emits any
jamming signals.
[0005] Hence, it is known to coordinate the transmission of jamming
signals from a plurality of cooperating vehicles. The prior art
also includes a solution as how to accomplish radar echoes with
angular errors. However, there is yet no technical solution for
automatically producing misleading jamming signals in order to
avoid hostile missiles or other weapons, which may operate in a
so-called Home-on-Jam (HOJ) mode.
SUMMARY OF THE INVENTION
[0006] It is therefore an object of the present invention to
alleviate the above problem and thus provide an efficient and
reliable solution for improving a vehicle's chances of evading any
HOJ-based weapon systems.
[0007] According to one aspect of the invention this object is
achieved by the method of producing jamming signals as described
initially, wherein the messages exchanged over the wireless data
link include data pertaining to a usage of at least one first
electronic warfare resource in a first station in the group and at
least one second electronic warfare resource in at least one second
station in the group. The method also involves coordinating the
usage of the at least one first and second resources based on the
messages and the time reference signal, such that a particular type
of jamming signal is emitted alternately either from the at least
one first resource or from the at least one second resource. This
altering of the origin of the jamming signal is performed
essentially without any overlaps or gaps in time between the
signals emitted from the different resources.
[0008] An important advantage attained by this strategy is that a
point of balance for the jamming signals is placed outside each of
the vehicles involved. Consequently, the jamming signals produce a
false target, and any HOJ-based weapon fired towards the vehicles
will most probably lock onto this false target, and therefore
fail.
[0009] According to a preferred embodiment of this aspect of the
invention, the method involves specifying signal parameter
information pertaining to a number of known threats; specifying a
counter measure library containing a complete set of electronic
warfare resources comprising any resources, which are included in
at least one station of the group; and identifying, for each of
said threats, at least one of the resources in the complete set of
electronic warfare resources, which is estimated to constitute an
appropriate counter measure to combat the threat. This procedure
(which preferably performed before instigating a mission) is
advantageous because thereby the chances of applying efficient
counter measures in each given situation are highly improved.
[0010] According to another preferred embodiment of this aspect of
the invention, the method involves specifying a time synchronizing
pattern describing a timing profile for a jamming signal to be
emitted from each resource in the complete set of electronic
warfare resources in respect of each threat. This is desirable,
since thereby further guidance is provided as how to best combat a
threat by means of coordinated emissions of jamming signals.
[0011] According to yet another preferred embodiment of this aspect
of the invention, the method involves specifying, in each station,
for each electronic warfare resource included in this station
whether the resource is currently available or not for emitting
jamming signals; and repeatedly exchanging status messages with the
other stations in the group. Each message here reflects a current
availability of the electronic warfare resource included in the
station from which the message is transmitted. The method also
involves recording, based on any received status messages from the
other stations in the group, a resource activation status for each
resource of the electronic warfare resource included in the other
stations in the group. Hence, all stations in the group remain
updated with information regarding the usage of the electronic
warfare resources in all the stations without a central control
mechanism being required. Naturally, this vouches for flexible and
reliable coordinated employment of the electronic warfare
resources.
[0012] According to still another preferred embodiment of this
aspect of the invention, each station in the group is associated
with at least one threat warning system. The method involves
determining in a first station in the group, based on an output
from the at least one threat warning system and the resources
activation statuses, whether at least one particular threat is
appropriate to combat by means of a first electronic warfare
resource in this station in coordination with at least one second
electronic warfare resource in at least one second station in the
group. If it is found that such a coordination is appropriate, a
request message is transmitted from the first station to the at
least one second station. Then, the first station waits for at
least one reply message to be returned from the at least one second
station in response to the request message. If at least one of any
received reply messages indicates a service accept, a jamming
signal is emitted from the first electronic warfare resource in
coordination with a jamming signal emitted from each of the at
least one second electronic warfare resource in the at least one
second station, which has replied with a message that indicates a
service accept. Thereby, coordinated signal emission from multiple
stations may be accomplished entirely without the involvement of a
central control mechanism. This, in turn, provides a very robust
system.
[0013] According to another preferred embodiment of this aspect of
the invention, the emission of the jamming signals is maintained
until the at least one threat warning system indicates that all
threats being combated by the jamming signals have ceased to
constitute threats, or a stop message is received from the at least
one second station in respect of the jamming signals. Thus, jamming
signals will be emitted only as long as required by the
situation.
[0014] According to yet another preferred embodiment of this aspect
of the invention, the coordination of the usage of the at least one
first and second resources involves determining an absolute point
in time when the emission of the particular type of jamming signal
shall begin. This coordination also involves determining a time
synchronizing pattern for the emission of the particular type of
jamming signal from the first electronic warfare resource and the
at least one second electronic warfare resource. Hence, the desired
illusion of a seemingly continuous signal transmission from a false
signal source can be created. Moreover, by varying the time
synchronizing pattern, so that a duty cycle of each electronic
warfare resource is modified over time, the false signal source's
position relative to the first and at least one second station may
be altered.
[0015] According to another aspect of the invention this object is
achieved by a computer program directly loadable into the internal
memory of a digital computer, comprising software for controlling
the method described above when said program is run on a
computer.
[0016] According to yet another aspect of the invention this object
is achieved by a computer readable medium, having a program
recorded thereon, where the program is to make a computer perform
the method described above.
[0017] According to another aspect of the invention this object is
achieved by an electronic counter measures station for radiating
jamming signals as described initially, wherein the communication
unit is adapted to exchange the messages with at least one other
electronic counter measures station, which is physically separated
from the station and is associated with the station to form a group
of stations. The messages include data pertaining to a usage of the
at least one first electronic warfare resource and at least one
corresponding second electronic warfare resource in at least one
other electronic counter measures station in the group. The station
also includes a resource handling unit adapted to, based on the
messages and the time reference signal, coordinate the usage of the
at least one first and second resources such that a particular type
of jamming signal is emitted alternately either from the at least
one first resource, or from the at least one second resource. The
station is adapted to carry out this altering of the origin of the
jamming signal essentially without any overlaps or gaps in time
between the signals emitted from the different resources.
[0018] The advantages of this station, as well as the preferred
embodiments thereof, are apparent from the discussion hereinabove
with reference to the proposed method.
[0019] Further advantages, advantageous features and applications
of the present invention will be apparent from the following
description and the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The present invention is now to be explained more closely by
means of preferred embodiments, which are disclosed as examples,
and with reference to the attached drawings.
[0021] FIG. 1 illustrates an electronic warfare situation, in which
the invention may be employed to evade a hostile weapon,
[0022] FIG. 2 shows time lines, which illustrate how a coordination
procedure according to the invention may be implemented,
[0023] FIG. 3 shows block diagrams over the stations in a group
which cooperate according to one embodiment of the invention,
[0024] FIG. 4 illustrates a proposed database to be included in
each station according to one embodiment of the invention,
[0025] FIG. 5 shows a block diagram over a counter measures
resources record according to one embodiment of the invention,
and
[0026] FIG. 6 shows a flow diagram over the general method
according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIG. 1 shows two air vehicles A and B respectively, which
each includes a proposed electronic counter measures station. It is
presumed that a threat warning system of at least one of the
vehicles A or B, say A, has registered a hostile air vehicle X,
and/or a missile mX fired from this vehicle X. We further presume
that each of the vehicles A and B is equipped with at least one
electronic warfare resource, and that the vehicles A and B
repeatedly exchange messages D indicating a current activation
status of these resources.
[0028] Moreover, each vehicle A and B is equipped with a database
including a threat library, which specifies signal parameter
information pertaining to a number of known threats. The database
also includes a counter measure library, which specifies a complete
set of electronic warfare resources that are carried either by the
vehicle A, the vehicle B, or both vehicles. A table in the
database, for each threat in the threat library, identifies at
least one of the resources in the complete set of electronic
warfare resources which is estimated to constitute an appropriate
counter measure to combat the threat.
[0029] Thus, based on an output from the threat warning system and
the table in the onboard database, the vehicle A can determine an
appropriate counter measure to combat the threat represented by the
missile mX and/or the vehicle X. In addition, the vehicle A can
determine whether suitable aiding counter measures are available in
the vehicle B on the basis of the messages D received from this
vehicle B.
[0030] For illustrating purposes we presuppose that appropriate
counter measures are available in both the vehicles A and B, and
that therefore electronic warfare resources in the vehicle A can be
coordinated with electronic warfare resources in the vehicle B to
combat the threat, which the missile mX and/or the vehicle X
constitutes. According to the invention, this means that a
particular type of jamming signals J.sub.A and J.sub.B respectively
are emitted alternately from either a resource in the vehicle A or
from a resource in the vehicle B essentially without any overlaps
or gaps in time. Provided that the signal sources are altered with
sufficient speed and accuracy, the missile mX and/or the vehicle X
will, as a result of this altering, conclude that the jamming
signals J.sub.A and J.sub.B originate from a single electronic
warfare resource which is located at a point of balance somewhere
between the vehicles A and B. Hence, provided that the threat mX
and/or X is guided by the jamming signals J.sub.A and J.sub.B (i.e.
is HOJ-operated), a false target AB.sub.X has been created with
respect to this threat that lies physically outside both the
vehicles A and B.
[0031] If both signal sources are located at equal distances from
the threat and transmit an equal amount of energy, e.g. by emitting
an equal signal power during equally long durations per period, the
false target AB.sub.X will appear to be located halfway between the
vehicles A and B. However, by varying the signals' time
synchronizing pattern, so that a duty cycle of each electronic
warfare resource is modified over time, the false target's AB.sub.X
position relative to the vehicles A and B can be altered, for
instance as shown in FIG. 1 where the false target AB.sub.X is
located closer to the vehicle A. This, of course, is an effect of
the signal energy emitted from the electronic warfare resource in
this vehicle A exceeding the signal energy emitted from the
electronic warfare resource in the vehicle B. In analogy, if a
first vehicle is estimated to be more proximate to a particular
threat than a second vehicle, the false target may appear to be
located halfway between these vehicles if larger jamming signal
energy is emitted from the second vehicle, i.e. the more distant
vehicle.
[0032] A prerequisite for accomplishing a sufficient time accuracy
(with errors less than milliseconds) in the altering of the signal
emission from the electronic warfare resources of the vehicles A
and B respectively, the vehicles need to receive a common and very
precise time reference signal. According to a preferred embodiment
of the invention, this signal is delivered by an external signal
source included in a global navigation satellite systems (GNSS),
such as the Global Positioning System (GPS; provided by the U.S.
Government), the Galileo system (provided by the European programme
for global navigation services) or the Global Orbiting Navigation
Satellite System (GLONASS; provided by the Russian Federation
Ministry of Defense).
[0033] Referring now to FIG. 2, the proposed coordinated use of
electronic warfare resources in different stations will be
discussed in further detail. The FIG. 2 shows a first time line
representing an electronic warfare resource of a first electronic
counter measures station, e.g. included in the vehicle A of FIG. 1,
and a second time line representing an electronic warfare resource
of a second electronic counter measures station, e.g. included in
the vehicle B of FIG. 1. Each time line illustrates an on-state
J.sub.A on and J.sub.B on respectively in which a jamming signal is
emitted from the resource in question, and an off-state J.sub.A off
and J.sub.B off respectively in which no jamming signal is
emitted.
[0034] Preferably, the vehicles A and B repeatedly (e.g. at regular
intervals) exchange messages during an entire mission, whereby the
messages reflect a current status and availability of the
electronic warfare resources included in the respective vehicle. As
long as no threat has been registered the electronic warfare
resources are typically inactivated, and thus the corresponding
messages D.sub.statusF indicate that these resources are available.
However, at a particular point in time, the first electronic
counter measures station deduces that a particular type of jamming
signals should be emitted to combat at certain threat, and that the
effect of such signals would be improved if they were emitted in
coordination with an available electronic warfare resource in the
second station. Therefore, the first station includes a request
message D.sub.req in a message sent to the second station.
Preferably, the request message D.sub.req specifies an absolute
point in time t.sub.J, which determines when the transmission of
the jamming signals shall begin. The request message D.sub.req may
also determine a time synchronizing pattern for the emission of the
jamming signals, so that each station knows how often, how long, at
which power, and possibly in which direction the signal is to be
transmitted. Alternatively, the time synchronizing pattern is
derived from an onboard database included in each station. Such a
database contains predefined time synchronizing patterns for each
combination of threat and counter measure. If the second station
itself is able to register and measure relevant parameters of the
threat, the direction in which to transmit the jamming signal is
preferably determined locally in the second station. Otherwise this
direction may be given in the request message D.sub.req. In
addition to addressee data (i.e. an identification of the second
station), the request message D.sub.req preferably contains a
reference number (to facilitate future reference to the efforts of
combating the threat in question), a threat identifier (which
uniquely describes the threat) and a designation of which type of
counter resource that is to be employed.
[0035] The message to the second station also specifies a current
status and availability D.sub.statusF of the electronic warfare
resources included in the vehicle A.
[0036] In response to the request message D.sub.req, the second
station returns a service accept message D.sub.acc, which confirms
that the particular resource will be engaged under the conditions
specified in the request message D.sub.req. Then, at t.sub.J, the
second station starts to emit the jamming signal according to the
determined time synchronizing pattern. According to an alternative
embodiment of the invention, the starting point ti for the
transmission is specified in the service accept message D.sub.acc,
instead of the request message D.sub.req. Namely, thereby tj may be
selected sufficiently far ahead to guarantee that the accepting
station is prepared to start the transmission at this point in
time. As can be seen in the FIG. 2, in this case, the duty cycle is
not entirely balanced between the stations. Instead, the first
station emits somewhat more signal energy than the second station.
As a result, the false target perceived by a HOJ-operated
threat/enemy weapon will appear to be located closer to the first
station than to the second station (compare with the FIG. 1).
[0037] During the period when jamming signals are emitted, the
stations continue to exchange message which indicate the status and
availability of their electronic warfare resources, i.e. which
resources that are presently used (or are unavailable for other
reasons) D.sub.statusR and available D.sub.statusF
respectively.
[0038] As soon as one of the stations, say the first station in the
vehicle A, has registered that the threat combated by the jamming
signals no longer exists (or at least does not constitute a
threat), this station includes a deactivation order D.sub.cutin the
message sent to the other station(s), i.e. in this case the second
station in the vehicle B. The deactivation order D.sub.cutspecifies
an absolute point in time t.sub.J-off when the transmission of
jamming signals should end. Thus, after this point in time
t.sub.J-off, none of the first or second stations emits any jamming
signals (at least not in respect of the threat in question).
However, the stations continue to exchange messages D.sub.statusF
that reflect the status and availability of their respective
electronic warfare resources.
[0039] Alternatively, a deactivation order D.sub.cut may be
generated by a station in respect of a first threat if this station
registers one or more higher prioritized threats, and therefore
cannot continue to combat the first threat. Nevertheless, the first
threat may still constitute a threat to the station itself as well
as other to other stations in the group.
[0040] Even though the FIGS. 1 and 2 only show two cooperating
stations, it is readily understood by the skilled person that the
proposed shifting of the jamming signal source between different
stations can be extended to three or more stations, so that in the
case of n stations the transmission cycle is divided into n
segments, each in which exclusively one station transmits a jamming
signal. Thus, in respect of a HOJ-operated weapon, a false target
is created which appear to be located physically separated from
each of the n stations.
[0041] FIG. 3 shows block diagrams over electronic counter measures
stations 100, 200 and 300 in a group of stations which are adapted
to cooperate according to one embodiment of the invention.
Specifically, the stations 100, 200 and 300 are adapted to radiate
jamming signals in coordination with one another, such that a
particular type of jamming signal is emitted alternately either
from at least one first resource, say R.sub.11, in one station
(e.g. 100); or from at least one second resource, say R.sub.21, in
another station, (e.g. 200) essentially without any overlaps or
gaps in time.
[0042] All the stations 100, 200 and 300 include essentially the
same devices and units. However, the number and types of resources
R.sub.11, . . . , R.sub.1l, R.sub.21, . . . , R.sub.2j; R.sub.n1, .
. . , R.sub.nk included in an electronic warfare system 140, 240
and 340 respectively of each station may vary.
[0043] Nevertheless, a first station 100 preferably includes (or is
associated with) at least one threat warning system 105. The first
station 100 also includes a database 110, an electronic warfare
system 140, a resource-handling unit 150, a receiver unit 160 and a
communication unit 170. The threat warning system 105 typically
includes an interception receiver, which is adapted to detect
signals emitted by potential enemy vehicles and/or missiles. The
electronic warfare system 140 includes at least one electronic
warfare resource R.sub.11, . . . , R.sub.1l, which is adapted to
generate and emit at least one type of jamming signal. The
resource-handling unit 150 is adapted to repeatedly control the
communication unit 170 to exchange status messages D with the other
stations 200, 300 over a wireless data link L. As mentioned above,
the messages D comprise data pertaining to a usage of the station's
100, 200, 300 electronic warfare resources. Specifically, a message
D transmitted from the first station 100 contains data pertaining
to a status and availability of the resources R.sub.11, . . . ,
R.sub.1n in the electronic warfare system 140. Correspondingly, a
message D transmitted from a second station 200 contains data
pertaining to a status and availability of the resources R.sub.21,
. . . , R.sub.2j in an electronic warfare system 240 of this
station, and so on. Typically, the frequency at which messages D
are exchanged over the link L depends on the number of stations
that are associated with one another to form a group, such that in
a relatively large group the update frequency is comparatively low,
and vice versa. However, the update rate normally lies in the
interval 1 to 2 seconds.
[0044] The receiver unit 160 is adapted to receive a wireless time
reference signal T from an external resource, such as a satellite
of a GNSS. The resource handling unit 150 is adapted to, based on
the messages D and the time reference signal T, coordinate the
usage of at least one first resource in the station 100 itself
(i.e. one of R.sub.11, . . . , R.sub.1l) and at least one of the
corresponding resources R.sub.21, . . . , R.sub.2j and R.sub.n1, .
. . , R.sub.nk of at least one of the other stations 200 and 300,
such that a particular type of jamming signal is emitted
alternately either from the first resource or from the at least one
second resource, essentially without any overlaps or gaps in
time.
[0045] According to a preferred embodiment of the invention, the
station 100 contains a database 110, which in turn, includes a
threat library 411, a counter measure library 412 and a table 413.
The details of this database 110 will be elucidated below with
reference to FIG. 4.
[0046] The threat library 411 specifies signal parameter
information pertaining to a number of known threats. The counter
measure library 412 specifies a complete set of electronic warfare
resources, containing any resources which are included in at least
one of the stations 100, 200 or 300 in the group, i.e. R.sub.11, .
. . , R.sub.1l; R.sub.21, . . . , R.sub.2j; R.sub.n1, . . . ,
R.sub.nk. Preferably, for each resource in the complete set of
electronic warfare resources R.sub.11, . . . , R.sub.1l; R.sub.21,
. . . , R.sub.2j; R.sub.n1, . . . , R.sub.nk, the counter measure
library 412 also specifies a time synchronizing pattern describing
a timing profile for a jamming signal to be emitted by the
resource. The table 413 in the database 110 identifies, for each
threat in the library 412, at least one of the resources in the
complete set of electronic warfare resources R.sub.11, . . . ,
R.sub.1l; R.sub.21, . . . , R.sub.2j; R.sub.n1, . . . , R.sub.nk
that is estimated to constitute an appropriate counter measure to
combat the threat. Thus, when the station 100 registers a threat,
e.g. by means of the warning system 105, the database may provide
information as how to best combat this threat, i.e. which
electronic warfare resources to use as well as the parameters for
the jamming signal(s) to emit.
[0047] Preferably, the database 110 is prepared before instigating
a certain mission, such that it stores as relevant and updated
information as possible. It is also highly preferable if
corresponding databases 210 and 310 in the other stations 200 and
300 respectively contain information which is identical to the
information in the database 110.
[0048] FIG. 5 shows a block diagram over a counter measures
resources record 550 to be stored in (or be associated with) the
resource-handling unit 150 according to one embodiment of the
invention. The record 550 contains a local resource listing 551 and
a group resource listing 552.
[0049] The local resource listing 551 specifies, for each
electronic warfare resource R.sub.11, . . . , R.sub.1l included in
the station 100, whether the resource is currently available or not
(i.e. if the resource is operable and free, or if the resource is
occupied or unusable due to technical problems). The group resource
listing 552 specifies an activation status for each electronic
warfare resource R.sub.21, . . . , R.sub.2j and R.sub.n1, . . . ,
R.sub.nk included in the other stations 200 and 300 of the
group.
[0050] The resource-handling unit 150 repeatedly (preferably at
regular intervals) checks the status of the electronic warfare
resource R.sub.11, . . . , R.sub.2l of the electronic warfare
system 140, and updates the group resource listing 552 accordingly
with a current resource activation status for each resource. This
data is also included in the messages D.sub.statusR and
D.sub.statusF, which are sent to the other stations 200 and 300
over the wireless data link L. Moreover, based on corresponding
messages received from the other stations 200 and 300 in the group,
the resource handling unit 150 repeatedly (preferably at regular
intervals) updates the group resource listing 552 with a current
resource activation status for each resource of the electronic
warfare resource R.sub.21, . . . , R.sub.2j and R.sub.n1, . . . ,
R.sub.nk included in these stations 200 and 300.
[0051] Hence, whenever the resource-handling unit 150 in the
station 100 determines that a threat exists, based on an output
from the least one threat warning system 105, the unit 150 may
consult the counter measures resources record 550 to find suitable
resources to combat this threat. If, on the further basis of the
database 110, the resource handling unit 150 finds that it is
appropriate to use one or more counter measures resources of the
other stations 200 and 300 to combat this threat, relevant requests
are sent out over the wireless data link L to these stations via
the communication unit 170 according to what has been described
above with reference to the FIGS. 1 and 2.
[0052] Returning again to the FIG. 3, each of the second 200,
third, etc. station up to an n:th station 300 associated with one
another in a group includes devices and units 205; 305, 210; 310,
220; 320, 230; 330, 240; 340, 250; 350, 260; 360 and 270; 370
equivalent to the devices and units 105, 110, 120, 130, 140, 150,
160 and 170 respectively described above with reference to the
first station 100.
[0053] In order to sum up, the general method for coordinating
electronic counter measures according to the invention will now be
described with reference to FIG. 6. It is worth noting that the
method illustrated in the FIG. 6 neither describes the steady-state
status messages exchanged between the stations nor the specific
messages exchanged in connection with initiating and ending of the
coordinated signal emission. Instead, the flow diagram discloses a
higher-level procedure, which is performed by a particular station
when detecting and combating a threat by means of electronic
counter measures being coordinated with at least one other
station.
[0054] A first step 605, evaluates a current threat status, for
instance via a threat warning system. Then, a step 610 evaluates a
current status of the electronic warfare resources, i.e. those
resources that are included in the station itself and those
resources that are included in any other stations belonging to the
same group as the station. This evaluation is preferably performed
by means of the above-described resource-handling unit.
Subsequently, a step 615 checks, e.g. based on the above-described
onboard database and the local resource listing, whether the
vehicle's own available electronic warfare resources are deemed to
be sufficient to combat the threat, and if so a step 620 follows.
Otherwise, the procedure continues to a step 640.
[0055] The step 620 effects the appropriate electronic warfare
resources on a singular basis, i.e. without coordination with other
stations. After that, a step 625 updates the local resource
listing, so that the fact that certain resources now are employed
can be reflected in status messages sent to the other stations. A
following step 630, checks whether it is still required to employ
the electronic warfare resources, and if so the procedure returns
to the step 605 while the jamming signal continues to be emitted.
Otherwise, a step 635 follows, which deactivates the electronic
warfare resources. Then, the procedure returns to the step 605.
[0056] The step 640 sends out a request for assisting electronic
warfare resources, i.e. resources included in at least one other
station. Such a request is primarily sent to one or more of those
stations, which based on the above-described group resource
listing, have available resources that are deemed appropriate to
combat the detected threat (based on the above-described database).
Then, a step 645 checks whether the request is accepted, i.e. if at
least one service accept message is returned, and if so a step 650
follows. Otherwise, the procedure continues to the step 620.
[0057] The step 650 coordinates the use of the electronic warfare
resources with the at least one other station that has returned a
service accept message according to what has been described above.
Subsequently, a step 655 effects the appropriate resources in
alternating coordination with the at least one other station, and a
step 660 updates the local resource listing accordingly, so that
the fact that certain resources now are employed can be reflected
in status messages sent to the other stations.
[0058] A following step 665, checks whether a deactivation order
has been received in respect of the jamming signals emitted by the
resources employed in alternating coordination with the at least
one other station, and if so the procedure continues to the step
635. Otherwise, a step 670 follows, which checks whether, based on
the onboard threat warning system, employment of the electronic
warfare resources still is required. If this is found not to be the
case, the step 635 follows. Otherwise, the procedure returns to the
step 605 while the jamming signal continues to be emitted.
[0059] All of the process steps, as well as any sub-sequence of
steps, described with reference to the FIG. 6 above may be
controlled by means of a programmed computer apparatus. Moreover,
although the embodiments of the invention described above with
reference to the drawings comprise computer apparatus and processes
performed in computer apparatus, the invention thus also extends to
computer programs, particularly computer programs on or in a
carrier, adapted for putting the invention into practice. The
program may be in the form of source code; object code, a code
intermediate source and object code such as in partially compiled
form, or in any other form suitable for use in the implementation
of the process according to the invention. The carrier may be any
entity or device capable of carrying the program. For example, the
carrier may comprise a storage medium, such as a Flash memory, a
ROM (Read Only Memory), for example a CD (Compact Disc) or a
semiconductor ROM, an EPROM (Erasable Programmable Read-Only
Memory), an EEPROM (Electrically Erasable Programmable Read-Only
Memory), or a magnetic recording medium, for example a floppy disc
or hard disc. Further, the carrier may be a transmissible carrier
such as an electrical or optical signal which may be conveyed via
electrical or optical cable or by radio or by other means. When the
program is embodied in a signal which may be conveyed directly by a
cable or other device or means, the carrier may be constituted by
such cable or device or means. Alternatively, the carrier may be an
integrated circuit in which the program is embedded, the integrated
circuit being adapted for performing, or for use in the performance
of, the relevant processes.
[0060] The term "comprises/comprising" when used in this
specification is taken to specify the presence of stated features,
integers, steps or components. However, the term does not preclude
the presence or addition of one or more additional features,
integers, steps or components or groups thereof.
[0061] The invention is not restricted to the described embodiments
in the figures, but may be varied freely within the scope of the
claims.
* * * * *